Calibration of the R/V ATHENA Speed Sensor

摘要

The Kenyon knotmeter on the R/V ATHENA was calibrated at sea. The calibration method is based on use of the ship's LORAN-C and CC-2 computer to provide a measure of ship speed relative-to-ground. However, the calibration procedure also accounts for ocean current speed and direction. Thus the technique results in an accurate measure of ship speed relative-to-water upon which the knotmeter calibration can be based. Calibration data indicate that the sensor is subject to friction and other factors which results in prior underestimation of speed through the water from about 1.5 knots at low speed (below 15 knots) to 2.25 knots at high speed (15 to 30 knots). This report presents both the method of calibration and the new Kenyon knotmeter calibration curve. The variation in the sensor output data is examined and recommendations are made regarding smoothing of the output data. (Author)